Daiso password notebook sells out as Japan's data leaks pile up

The timing matches the news. According to MM Research Institute, cyberattack-related leak cases in Japan rose from 72 in August and 81 in September to 193 in October. Leaked credentials such as passwords and login IDs reached about 161 million by the end of October, roughly 31 times the 5.14 million for all of 2025. One of the biggest cases: Sourcenext said on October 15 that up to about 22.52 million member records, including passwords, may have leaked.

Is writing passwords on paper safe?

Japan's Information-technology Promotion Agency (IPA) says its view hasn't changed since 2022: it does not necessarily rule paper out. It recommends a different password for every service, around 15 characters mixing upper and lower case letters and numbers. Password manager apps are fine too, it says, if you pick a trustworthy service with proper support.

Paper has weak spots. Carry the notebook around and you risk losing it or having someone peek. And a notebook can't help when a service itself is breached. Attackers take the leaked ID and password pairs and try them on other sites, a method called credential stuffing. Muji confirmed this kind of attack on its online store in November, and it is suspected on the official lottery site.

IPA's advice is to switch on multi-factor authentication or passkeys wherever a service offers them, and to treat unexpected emails and text messages as fake rather than opening their links.